Say I’m next to a car, with ten gallons of gas in the tank. The bad guys, attempting to kill me before I can retrieve the Pearl of Persia, shoot at the car, hitting the tank and causing it to explode (let’s ignore the improbability of an explosion occurring). How far do I have to be away from the car to avoid serious injury or death? From what I can tell in the movies, I’m either completely safe right next to it, or dead if I’m within a mile of it.
Sua
This being movie physics, all you have to do is run down a hallway and turn a corner and the fireball will shoot past you.
This depends on the type of explosion. And since the type of explosion caused by shooting a car does not exist, the question is impossible to accurately answer.
You’ll have to revise your question a bit if you want a decent answer.
I think incendiary/tracer rounds would do the trick. IIRC Mythbusters did an ep. on exploding cars…
Yeah. Linky
Problem is in the movies hardly anybody is shown firing such ammunition-it typically is
standard issue handgun ammo, which won’t do the job.
I am a stickler for precision, too, but **SuaSponte ** explicitly set aside the issue of the cause of the explosion.
So the revision is:
Suppose, for whatever reason you may prefer to imagine, a car’s gas tank explodes. Let’s say something really implausible happens, something nobody would really do, like sawing a car in half with a power saw. Then what would the kill zone be?
Tackling the problem logically, it might be helpful to note that injury from explosions generally come from one or more of 3 things – heat/fire, concussion, and shrapnel.
My understanding is that the heat and concussion fall off fairly quickly with distance in normal explosions, but the shrapnel can have an extended effect.
I’m not sure where I’m going with this.
SUBMIT
But that’s just it. You can’t set aside the issue of the cause. The cause has too much to do with the resulting explosion–it’s power, it’s force, and it’s damage–to just ignore.
A gas tank will explode differently if you saw into it (like that video) than if you shoot it with some tracer round. Also, the size and type of the round will also change the explosion.
It all depends on the amount of heat and pressure applied and how quickly it is applied.
I’ve seen cars shot to hell by .50 cal and they caught fire and burned. But nothing I would consider an explosion. It was standard ammo, though, not tracers.
Gasoline in liquid form does not typically explode like a high explosive does. It is possible for gasoline to detonate (this is what causes “knocking” in car engines) but the pressures for this are very high, much higher than you’d get by simply igniting an open container of gasoline.
The big, flowery, red-black movie explosions you see are the result of the F/X guy putting a small quantity of high explosive–usually some very stable form of demolition-grade plastique, or high brisance-rated dynamite–underneath a small container of kerosene or fuel oil. The detonation aerosolizes the liquid into a big cloud of droplets and then sets them on fire, causing a massive explosive deflagation (rapid burning) which produces the impressive effect. This looks impressive but is actually very controllable and predictable, making it relatively safe to use on a populated set. In fact, some explosions aren’t even explosions; in Terry Gilliam’s Brazil, for instance, the explosive effects (used on a very crowded set and in a historic building) were actually large flame machines that produces an impressive display but essentially no pressure wave.
Real high explosives make very little flash–in slow motion capture, it’s basically a big grey-brown or black wall of detritus and compressed air–and a sharp, anechoic bang, throwing shrapnel at hundreds of feet per second, posing a hazard to anyone within a couple hundred feet or more. When performing demoliltion activities, it’s imperative to clean the site of all FOD (foreign object/debris) to reduce the hazard of flying shrapnel.
Stranger
Since we are on the topic of explosive hollywood automotive issues. The other exploding car scenarios is the flipped car with the dripping gas and the open flame. Would that explode as easily as Hollywood wants us to think? What the kill zone for that one?
All you have to do is run as fast as you can and then leap right when the car explodes (in slow motion, of course) and you will survive unhurt. Or, better yet, dive into a convenient body of water and the fireball will pass over you.
At least that’s how Arnold, Sly and the rest survive.
Didn’t Frank Rosenthal survive a carbomb? IIRC, he was close to his car when it blew. Not the gas tank but still…
Asked and answered; cars can burn furiously, but don’t “explode” like you see in movies (unless, as in the case of the Rosenthal kill attempt, someone actually puts a bomb under the seat). I see one or two cars a month on the side of the 10 highway that have caught fire and burned (and on a few occasions, one in the process of combusting) and no exploding has occurred. On the other hand, truely massive conflagrations of oil or fertilizer, where temperatures from burning get into the thousands of degrees, can result in impressive explosions, but this requries far more heat and fuel than you’ll get from a single car wreck.
Stranger
As Stranger said, auto fuel tanks don’t explode as shown in movies. Liquid gasoline doesn’t burn. Gasoline vapor mixed with the proper amount of air burns very rapidly. If the burning is confined so that the pressure builds up high enough the combustion rate shoots way up and you get a detonation. Nowever most fuel tanks will rupture long before that point is reached and you spill gasoline and fire all over the place. That isn’t to say that such an event isn’t spectacular in its own right, but it isn’t really a true explosion.
You know, this post was pretty misleading. I thought you were saying they actually made a car blow up by shooting it in the gas tank with a tracer round.
I was pretty surprised, but it didn’t sound impossible.
Not until just now did I check it out to see that they are saying pretty much the same thing I’ve seen. Engulfed in flames, but no explosion.
Their guess that if the tank didn’t have so many holes in it, then it surely would have exploded so it’s partly confirmed is bullshit. If they want to confirm it, do it again with a sealed gas tank. God, I hate those fucking Mythbusters retards.
“oooooh, if we make something burn or crash, it’s Science!” :rolleyes:
Going on my faultless memory of the book I read in college, has was actually in the car when it exploded, but was saved by a steel plate under the driver’s seat.
The laws of movie physics don’t act equally upon all characters, so it matters a great deal who you are. If you’re the hero or a puppygod, you’re safe starting from right next to the exploding car, because you’ll outrun the fireball (if appropriate, leaping in slo-mo as erie774 mentioned).
If you’re the hero’s cop buddy with less than a week to go before retirement to that house in the country you’ve been talking about for decades, then you’re toast from a mile away.
Explosions can do things that are just as odd as those done by tornados.
We had a plane crash on takeoff, catch fire and spill 1000 lb bombs out on the ground. An engineer fire crew was spraying water on one of the bombs from a distance of about 30 ft. when it went off. The guy on the nozzle had busted eardrums but was otherwise only shaken up. Everyone else on the crew was killed, and they were all behind him.
Hitler was saved because the briefcase full of explosive was in someone’s way and he moved it. This placed a table leg between the bomb and Hitler when it went off and he was shielded enough to be only injured.
In your first sentence remove the word typically. Liquid gasoline does not explode. It does not even burn. Only gasoline vapor when mixed with a proper amount of air in a fairly narrow range of air fuel mixtures will burn. To get it to detonate you have to raise the pressure/temperature past the point of where the anti-knock agent are effective.
Here in the real world, cars do not explode. They don’t explode when hit by gunfire, they don’t explode in mid air after going off a cliff, and the don’t explode in mid-roll after an accident.
Chips was not a documentary.
I can tell you, from personal experience, that an upsidedown car (or, in my case, a minivan) dripping gasoline with the engine running doesn’t blow up. Mine was in that state for 20 minutes before anyone thought to turn the engine off. It continued to drip gasoline until the tow people righted it and took it away about an hour later.
Of course, that excludes the open flame, but the sparks from dragging metal across pavement through the gasoline didn’t do it either. The tow people, and the fire dept didn’t seem at all concerned.
My husband tells me that an empty (or nearly empty gas tank is more likely to explode than one with gasoline in it.
Using movie physics, you need to be just far enough away that the fireball completely fills the screen behind you. Exactly how far that away depends on how much witch’s brew the sfx guys use. Whether or not you make it that far, or survive the explosion, depends on how far into the movie you are and whether you’re a main character or not.